Electric cable



July 31, 1934. Q El BENNETT 41,968,019

ELECTRIC CABLE Filed Dec. 27, 1952 4, will ATTORNEYS.

Patented Jury 31, 1934 AUNITED sTATEsQPArr-:Nr opp-'ICE 1,968,019v `v 4ELECTRIC CABLEy Charles E. Bennett, Hawthorne, N. J., assignor to TheOkonite-Callender Cable Company, Incorporated, Paterson, N. J., a-corporation of New Jersey Application necember'l'zr. 1932, serial No.648,897

conductors are maintained submerged in an in-v sulating uid such as oilwhich is constantly maintained under high pressure.

li In thesystem of the present applicationI propose to provide a sealedenclosure filledwith oil i or other insulating fluid and in which theinsulated conductor is submerged, the' present invention providing forpermitting the casing or enclosure to expand under temperature rises andto return to its original size when temperature returns to normal toprovide a breathing action, thereby toinsure that the insulation of theoonductor or conductors will be maintained lled with insulating fluid atall times and that voids and gas pockets in the insulation will beavoided. In the accompanying drawing in which I have shown severalembodiments of my invention:

Fig. 1 is across section `of one embodiment of the invention;

Fig. 2 is a similar view of a modification; 'and Fig. 3 is a similarview -of still another embodiment of the invention.

Referring to the drawing in detail and rstmf all to Fig. 1, my vimproved'cable which for purposes of illustration has been shown as a threeconductor cable, comprises conductors 1, 2 and 3, insulated by oilimpregnated paper, for example, 4. The insulated conductors'are drawninto'a tubular casing, pipe or enclosure 5 of ferrous metal, such assteel, for instance, of the necessary wall thickness to withstandwhatever pressures it may be desired to operate at but at the same timeof sulllcient elasticity to permit of the desired movement underpressure increase. I have shown an oval pipe for purposes ofillustration but it will be understood that the pipe -5 may take otherforms, the intent being to provide a pipe capable of being distortedunder high pres,- sure and of returning to initial condition when thepressure drops( The pipe 5 is iilled with oil or other insulating .fluid6 in which the linsulated conductors 1, 2 a'nd 3 are submerged.

If 'an initial pressure is applied to the insulating fluid it'willy beof ,the vorder mentioned in l1 Claims. (Cl. 247-3) my copending,application above referred to, say for example, ve atmospheres minimumup to several hundred pounds maximum, such pres- -1 sures beingsuliiciently high to increase the dielectric strength of the oil. w

As understood by those skilled in this art the operation of high tensioncables causes the insulating uid of the cable to expand in volume, the

lfluid returning to its original volume during the coolingcycle. I 4wishto avail myself of these 65 changes in volume of the fluid insulatingmedium of the cable. Consequently I construct the pipe 5k of steel orother elastic material capable of being expanded by the pressures builtup in the insulating uid on the heating cycle and of re- 'I0 A turningto its initial or normal shape on the cooling cycle. Employing apipesuch as illustrated in the drawing it 'will be seen that when 'the fluid6 in which the conductors are submerged heats up to increase its volume,the increase in pressure which results will expand the pipe 5 from thefull line position to the dotted line position of Fig. 1.-

On the cooling cycle the pipe will contract or return to its originalshape due to the elasticity A of the material of which it isconstructed, thereby to provide a pulsating or breathing action tendingto prevent the formation of voids or gas pockets in the insulation ofthe cable and insuring very desirable working conditions" at all. times.Furthermore, if the oil Sis maintained under a pressure of the orderabove referred to, then it will be understood that not only will thebreathing action above referred to be morel pronounced but .I am assuredof the benet of 90 an increase in the ldielectric strengthof the oilresulting from the high pressure employed. In the embodiment of myinvention illustratedV v in Fig. 2 I employ the same type. ofconstruction as just described. except that I partially nll the tubularcasing or pipe 5 with a filler 7 of coarse sand, stone, or any othersuitable freely movable solid material which does not pack readily so asnot to destroy vor'interfere with the desired direct contact of the bodyof insulating uid 6 with 100 the exterior of the insulating envelope 4of each conductor. The filler 7 reduces the volume of insulating fluid 6necessary to ll the pipel 5, without sacrificing the area of theradiating surface of the pipe. The filler 7, particularly where sand isemployed, for example, may be mixed with the insulating uid 6 and thetwo materials introduced together into the casing 5, the sand particles,as will be understood, settling to the bottom of the casing.

In the embodimentoi' my invention as illustrated in Fig. 3 I have showna pipe 5, and insulated conductors l, 2 and 3, this pipe being ovalshaped, as distinguished from round, but instead of making the Wall ofthe pipe elastic it may be rigid, the purpose-of this construction beingto provide a very extensive heat radiating surface and a relativelysmall amount of oil as compared 'with a round pipe having the` sameradiating surface.

It is to be understood ofcourse that in this embodiment of my inventionhaving the insulating fluid initially at atmospheric pressure, or

jinitially under pressures, such ras above mensufllcient to increase thedielectric4 other than oval may be employed Within the purtrical energy,said system comprising in combination a conductor, oil impregnatedinsulation for the conductor, an all elastic metal non-circular tubularcasing loosely enclosing the conductor and its insulation, liquidinsulation in said casing and in which the conductor and its rinsulationare submerged, said enclosing casing expanding toward circular crosssection by the building up of pressure in the casing due to heating oftheliquid insulation on the heating cycle of the cable, to increase thecapacity of the casing, the casing contracting to its original capacityon the cooling cycle.

2. A cable system of the oil filled type for the undergroundtransmission of high tension electrical energy, said system comprisingin combination a conductor, oil impregnated insulation for theconductor, an all elastic metal noncircular tubular casing of uniformAwall thickness loosely enclosing the conductor and its insulation,`liquid insulation in said casing and in which the conductor and itsinsulation are submerged, said enclosing casing expanding towardscircular cross section by the building up of pressure in the casing dueto heating of the liquid insulation on the heating cycle of the cable,to lincrease the capacity of the casing, the

ycasing contracting to its original capacity on the cooling cycle. y f

3. A cable system of the oil lled type for the underground transmissionof high tension electrical energy, said system comprising in combinationa'plurality of unsheathed cable conductors of the solid stranded type,oil impregnated insulation foreach of said conductors, an all elasticmetal non-circular tubular casing loosely enclosing said conductors andtheir insulation, liquid insulation in said casing and in which theconductors and their insulation are submerged, said enclosing casingexpanding toward circular cross section by the building up of pressurein the casing due to heating of the liquid insulation on the heatingcycle of the cable, to increase the capacity of the casing, the casingcontracting to its original capacity on the cooling cycle.

4. A cable system of the oil lled type for the underground transmissionof high tension electrical energy, said system comprising in combinationa 4plurality of unsheathed cable conductors of the solid stranded type,oil impregnated insulation foreach of said conductors, an all elasticmetal non-circular tubular casing loosely enclosing said conductors andtheir insulation, liquid insulation in said casing and in which theconductors and their insulation are submerged, means for maintainingsaid liquid insulation under pressure, said enclosing casing expandingtoward circular cross section by the building up of pressure in thecasing due to heating of the liquid insulation on the heating cycle ofthe cable, to increase the capacity of the casing, the casingcontracting to its original capacity on the cooling cycle.

5. A cable system of the oil iilled type for the undergroundtransmission of high tension electrical energy, said system comprisingin'combination a plurality of unsheathed cable conductors of Vthe solidstranded type, oil impregnated in sulation for each of said conductors,an all elastic metal non-circular tubular casing loosely enclosing saidconductors and their insulation,'liquid insulation in said casing and inwhich the conductors and their insulation are submerged, means formaintaining said liquid insulation under suiiiciently high pressure toincrease its dielectric strength, said enclosing casing expanding towardcircular cross section by the building up vof pressure in the casing dueto heating of the liquid insulation on the heating cycle of the cable,to increase the capacity of the casing, thel casing contracting to itsoriginal capacity on the cooling cycle.

6; A cable system of the oil lled type for the underground transmissionof high tension electrical energy, said system comprising in combi-` andtheir insulation, a loosely packed freely movable solid material Withinsaid` casing for reducing the capacity thereof, and liquid insulationfilling the space in said casing unoccupied by the insulated conductorsand said loosely packed solid material, said conductors and theirinsulation being submerged in said liquid insulation and loosely packedsolid material, said enclosing casing expanding toward circular crosssection by the building up of pressure in the casing due to heating ofthe liquid insulation on the heating cycle of the cable, to increase thecapacity of the casing, the casing contracting to its original capacityon the cooling cycle.

7. In the installation of multi-conductor high tension electric cablesystems the method which i a.. In the instauacionfof multi-conductorhigh tension electric cable systems the method which comprises drawing aplurality of unsheathedy conductors each provided with permeableinsulation into a pipe line and lling the spaces in the'y pipe lineunoccupied bythe conductors and their insulation with oil and a looselypacked freely movable solid material so that the conductors and theirinsulation are at all times submerged in said oil and loosely packedmaterial, and placing the oil under a pressure not substantially lessthan ve atmospheres to increase its dielectric strength.

9. A multi-conductor high tension electric cable system comprising incombination a plurality of unsheathed cable conductors each conductorbeing independently insulated with permeable impregnated insulatingmaterial, a pipe line enclosing said conductors, the internal diameterof said pipe line relatively to the space occupied by the conductors andtheir insulation being such as to permit of said insulated conductorsbeing drawn into the pipe line, oil and a loosely packed freely movablesolid material filling the space unoccupied by said conductors and theirinsulation and in' which the conductors and their insulation aresubmerged and in which the insulated conductors have free movementrelatively to each other, and means for maintaining said oil undersufficiently high pressure to increase its dielectric strength.

10. A multi-conductor high tension electric cable system comprisingin-ccmbination a plurality of unsheathed cable conductors of the solidstranded type each conductor being independently insulated withpermeable impregnated insulating material, a pipe line enclosing saidconductors, the internal diameter ot said pipe line relatively to thespace occupied by the conductors and their insulation being such as topermit of said insulated conductors being drawn into the pipe line, oiland a loosely packedfreely movable solid material illling the. spaceunoccupied by said conductors and their insulation and in which theconductors and their insulation are submerged and in which the insulatedconductors have free movement relatively to each other, and means formaintaining said oil under a pressure of not' substantially less than veatmospheres to increase its dielectric strength.

ll. A multi-conductor high tension electric cable system comprising incombination a plurality of unsheathed cable conductors of the solidstranded type each conductor being independently insulated withpermeable impregnated insulating material, a pipe line of elastic metalenclosing said conductors, said' pipe line being sutilciently elastic topermit it to change its capacity in accordance with variations in thevolume of the liquid insulation by reason of thermal changes in thesystem, the internal diameter o! said pipe line relatively to the spaceoccupied by the conductors and their insulation being such as to permitoi' said insulated conductors beingdrawn into the pipe line, oil and 'aloosely packed freely movable solid material iilling the spaceunoccupiedl by said conductors and their insulation and in which theconductors and their insulation are submerged and in which the insulatedconductors have free movement relatively to each other, and means formaintaining said oil under a pressure of not substantially less thanfive atmospheres to increase its dielectric strength.

CHARLES E. amm.

